1. Field of the Invention
The present invention relates to a motion compensation device which compensates for motion caused by hand shake and the like in a camera or other optical device. More particularly, the present invention relates to a motion compensation device which compensates for motion of an image on an image forming plane without using special sensors, such as angular velocity sensors, to detect motion.
2. Description of the Related Art
Cameras having motion compensation devices are known. A conventional motion compensation device compensates for motion causing blurring of an image on an imaging plane, which occurs as a result of vibration of the camera during photography, by driving a motion compensation optical system (referred to hereinbelow as "motion compensation lens") which constitutes a portion of a photographic optical system.
The conventional motion compensation device detects hand shake with angular velocity sensors or acceleration sensors, or the like, and calculates a drive signal based on the detected hand shake. The conventional motion compensation lens is supported such that movement at approximately right angles to the optical axis is possible. An actuator drives the motion compensation lens, based on the drive signal, in a direction which cancels the motion causing blur of an image formed in the imaging plane (e.g., a film plane).
The motions of the camera which are the origin of image blur during photography are pitching, yawing and rolling motion, motion parallel to the vertical, motion parallel to the horizontal, and the like. Pitching and yawing motion are so-called angular motion. When photographing at long range, and when the lens focal distance is long, pitching and yawing motion have the effect of producing large motion of an image on the imaging plane (film plane) relative to the optical axis, and, as a result, a large amount of image blur in the imaging plane. Because angular motion is motion producing an angular velocity, the conventional motion compensation device determines the motion angle caused by pitching and yawing motion using two angular velocity sensors respectively detecting angular velocity in two axial directions, and by integrating the output signals of the angular velocity sensors. The motion compensation lens is then driven to cancel the movement of the optical axis accompanying the movement of the camera to prevent movement of the image in the film plane. Many prior art motion compensation devices compensate only the effects of pitching and yawing in the above-described manner.
A conventional motion compensation device requires angular velocity sensors or the like sensors in order to detect motion. However, angular velocity sensors and the like are expensive sensors. Therefore, a problem arises in that cameras and other optical instruments having a motion compensation device are expensive.